engleski

Mixed Ion-Polaron Charge Transport in Silver Zinc Phosphate Glasses Containing WO3 and MoO3

The subject of this study is to investigate the influence of the addition of two different transition metal oxides, WO3 and MoO3, to silver zinc phosphate glasses. Such glasses, due to their mixed ion-polaron transport, exibit interesting electrical properties which are of interest as potential cathode materials in solid state batteries. Two different conductions, ionic and electronic, contribute to total conductivity in these glasses. Ionic conductivity depends on the mobility and concentration of silver ions, whereas electronic one follows small polaron hopping mechanism.Glasses of general composition (30- 0.5x)Ag2O-(30-0.5x)ZnO- 40P2O5-xTMO (TMO = WO3, MoO3, 0≤x≤60 mol%) were studied. Their electric properties were studied with impedance spectroscopy in a wide frequency (10-2-106 Hz) and temperature (303-513 K) range. Method used for structural analysis was Raman spectroscopy while the fractions of reduced state transition metals were determined by EPR and SQUID measurements. Impedance spectroscopy measurements revealed different conductivity trends in studied glass series. In series with added WO3, DC conductivity decreases with the addition of WoO3, reaching minimal value between 30-40 mol% of WO3. With further increase of WO3 content above 40 mol%, DC conductivity rapidly increases due to increase of polaronic contribution to total conductivity. On the other hand, MoO3 glasses show a different trend. Addition of MoO3 to silver zinc phosphate glasses results in linear decrease in DC conductivity up to 50 mol% of MoO3 which shows that in this compositional range DC conductivity strongly depends on the decrease of silver ion concentration. At 60 mol% of MoO3 the glass is purely polaronic and the conductivity increases as a result of easy conduction pathways for polarons.

Mixed ion-polaron glasses ; Electrical conductivity ; Impedance spectroscopy ; Structure

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